1. Field of the Invention
This invention relates generally to methods and apparatus for reducing or eliminating hazards inherent in disposal of infectious waste. More particularly, the invention relates to a system which physically alters the infectious waste to reduce it to particulate matter and kills pathogens in the waste so that it can be safely disposed of in a conventional manner, for example in a sanitary landfill.
2. Discussion of Related Art
In disposal of infectious waste, specifically waste produced incidental to medical research, testing, and treatment for example, it is recognized that hazards are inherent in handling and disposition of such waste. This is due for example to the physical nature of the waste, which may include sharps which may cause injury and ready transmittal of pathogens due to accidental wounds; and also due for example to the amount and nature of pathogenic material which may be contained in the waste, and transmitted by contact or by airborne transmission to persons exposed to the waste without due precautions being taken. The hazard may persist as long as conditions conducive to continued existence of the pathogens persist. Accordingly, disposal by customary means into a sanitary sewer, and/or into a sanitary landfill may pose immediate and long-term health risks. Consequently methods and apparatus for rendering medical waste less hazardous have been developed, and new methods which more effectively mitigate the above-mentioned hazards are the subject of intense interest by persons concerned with disposal of such waste and the protection of public health and the physical environment.
Systems for disposal of medical waste have heretofore generally involved a number of treatment steps, each step requiring apparatus to effect the step. For example, a presently known treatment apparatus can include: a shredder for opening vials and other assorted containers and bags; a system for applying disinfectant, usually involving a sump and recirculation system to collect excess disinfectant, which may be mixed with waste fluids; a means to render excess fluid safe for disposal and transfer to a sanitary sewer; a hammermill or other means to pulverize solid waste, a pressure vessel wherein waste and disinfectant are subjected to a superatmospheric pressure to improve disinfectant penetration into voids; and a separator to separate solids from fluids and excess disinfectant, and means to transport waste to and from all the aforesaid during the treatment process. As can be appreciated, such an apparatus is usually large, and also relatively costly due to the number of treatment steps which must be provided for. Such an apparatus takes considerable space and may be uneconomical for smaller medical facilities to acquire and operate.
Furthermore, known infectious waste treatment systems generally have a limited capacity, for example in the range of eight hundred to twelve hundred pounds per hour. This is in spite of their relatively large size. This is due to time required to separate fluids from solids in known systems for example. A system which more speedily neutralizes hazards attendant handling and disposal of the waste will reduce the trouble and cost involved and encourage proper disposal of waste. For example, a smaller system would be advantageous in terms of both cost and space required, if adequate capacity can be maintained. Likewise operator time required can be reduced if waste is processed faster.
Moreover, it has been recognized that a system which is simplified in comparison with known systems would give further advantages over known systems in terms of both initial cost and operational cost over the life of the system. For example known systems with numerous treatment steps and components to carry them out are susceptible to a like number of equipment failures. This can cause difficulty beyond the system itself, as a backlog of infectious waste building up due to a disposal equipment problem can disrupt day-to-day operation of a facility producing such waste.
Another problematic aspect of some known systems is that periodically disinfectant must be dumped and fresh disinfectant supplied. As mentioned, disinfectant may be mixed with fluids from the waste. As will be recognized by those skilled in the art elimination of the need to periodically dump and refresh the disinfectant would avoid the further complication of the treatment process it represents.
Elimination of the need for access to a sanitary sewer line has also been recognized as a desirable objective, as this will reduce costs in many installations. Further, introduction of a powerful disinfectant chemical may have a deleterious effect on desirable biological processes in treatment of effluent from the sanitary collection system where the disinfectant is introduced.
What is needed, and has heretofore not been available, is a system that mitigates these problems. The present invention is directed to fulfilling this need.
Briefly, and in general terms, the present invention accordingly provides in combination an impactor adapted to pulverize the infectious waste by impact and an injector adapted to inject treatment fluid into the infectious waste and a mixer adapted to mix pulverized waste with treatment fluid. The system also includes a pressurizable drum having an interior configured to hold pulverized waste and treatment fluid at a superatmospheric pressure and an air pump adapted to apply a surcharge of air to the pressurizable drum to create a condition of superatmospheric pressure within the pressurizable drum, whereby improved absorption of treatment fluid by the pulverized waste and pathogenic organisms contained therein is enabled.
In a more detailed aspect the mixer can comprise said pressurizable drum, so that pressurization can be performed in the same container as mixing. In this instance waste is fed into the impactor where it is pulverized, treatment fluid is added, which treatment fluid comprises a substance which kills pathogenic organisms, and the mixture is transferred into the mixing drum. The waste and treatment fluid are mixed, then subjected to pressure, and then discharged from the mixer. The treated waste is moist and pulverized to a point where the waste is unrecognizable. The pathogenic organisms in the treated waste being killed, the waste can then be disposed of as ordinary waste.
These and other aspects and advantages of the invention will become apparent from the following detailed description, and the accompanying drawing figures, which illustrate by way of example the features of the invention.